I'm looking at buying a set of brakes for my road bike project. It seems I can get a set of lower-end campagnolo calipers for a good price, with the "mirage" as the cheaper option and the "centaur" a few bucks more. both look nice. the only difference I can see is in the pads--the mirage seems to have pads where the bolt sticks out of the rubber, and the centaur has cartridge types. Does anybody know if there is another difference? Is there an advantage to the cartridge, and is it worth paying more for?